Manufacture of razor blades



Nov. 8, 1966 M. R. HOBBS 3,283,665

MANUFACTURE OF RAZOR BLADES Filed Nov. 10, 1964 E L7 L2 L3 4 1 if w T I/ W N T R7 R2 R3 United States Patent 3,283,665 MANUFACTURE OF RAZOR BLADES Maynard Richard Hobbs, Twickenham, Middlesex, England, assignor to The Gillette Company, Boston, Mass., a corporation of Delaware Filed Nov. 10, 1964, Ser. No. 410,123 Claims priority, application Great Britain, Nov. 12, 1963, 44,596/ 63 7 Claims. (CI. 90-24) This invention relates to the production of razor blades by a process which involves the sharpening of one or both longitudinal edges of a metal strip of great length, the individual blades being separated from one another only after the sharpening operation has been completed.

According to the most widely used present manufacturing practice, a strip of steel having the same thickness and substantially the same width as the finished blades required is first notched and apertured to give it the form of a succession of blades joined together end to end. The strip is then subjected to heat treatments to harden and temper it and subsequently one, or each, longitudinal edge of the strip is subjected to a succession of operations for sharpening it to a cutting edge, the individual blades being then parted off from the strip. The manufacturing process may, and commonly does, include other steps such as printing upon the face of the strip and applying protective coatings.

To sharpen an edge of the strip, the strip is first moved past a grinding wheel rotating about an axis parallel to the direction of movement of the strip and so positioned that it cuts a bevel on one face of the strip adjacent the edge to be sharpened. The strip then moves past a second similar grinding wheel which cuts a corresponding bevel on the opposite face of the strip, the edge of the strip left between the two bevels being greatly reduced in thickness, but still blunt. The strip is then moved past a second pair of grinding wheels rotating about longitudinally disposed axes, arranged to form a sharp edge upon the strip by cutting a second pair of bevels or facets, which are narrower and are inclined at a greater angle to the plane of the strip than those out by the first pair of grinding wheels. The strip is then subjected to a honing operation which forms a third facet upon each face of the cutting edge. In the case of double-edge blades, these operations are, of course, repeated upon the other edge of the strip.

Nearly all the metal which must be removed from the strip in order to form the cutting edge is removed by the first pair of grinding wheels, which are consequently subject to heavy wear. The production of a satisfactory final cutting edge is dependent upon accurate formation of the primary bevels and it is consequently necessary to readjust the setting of the grinding wheels at very frequent intervals, requiring the full time attention of a highly skilled operator, or the provision of elaborate mechanisms for automatic re-adjustment.

In accordance with the present invention the thickness of the (or each) edge of strip is reduce-d by moving the strip longitudinally past and between a pair of cutting edges each disposed transversely to the said strip to remove material from opposite surfiaces adjacent the longitudinal margin thereof; a sharpened edge is produced along the said margin of the strip, and subsequently the strip is severed transversely of its length to produce a plurality of individual blades. A cutting tool formed of suitable hard material, such as a metallic carbide, is capable of cutting a bevel to the required degree of accuracy upon at least several hundred feet of strip before it requires re-adjustment or re-sharpening and the invention includes the use of simple outing tools which remain "ice fixed in position during use and have cutting edges which do not greatly exceed in width the width of the bevel to be out upon the moving strip. However, it is preferable to form each cutting tool :as a wheel or disc, having a circular cutting edge, only a very small part of which is in use at any moment. The cutting edge can then be re newed simply by rotating the cutting wheel about its axis, so as to bring a fresh part of its periphery into position to act upon the strip. Such rotation of the cutting wheel may be effected either continuously, or intermittently, and either automatically or under manual control.

The invention, whose scope is defined in the appended claims, includes both a novel method of manufacturing razor blades and apparatus for carrying out the method and a preferred manner of carrying the invention int-o efiect is described below, by way of example only, with reference to the accompanying drawings, in which:

FIGURE 1 is a somewhat diagrammatic plan view of the apparatus;

FIGURE 2 is a sectional view taken on the line IIII of FIGURE 1; and

FIGURES 3, 4 and 5 are sectional views, greatly enlarged, of one longitudinal marginal portion of the metal strip at dilferent stages in the manufacture.

In this embodiment of the invention, which embodiment is concerned with the production of doublecdged razor blades from carbon steel, primary bevels are formed on the strip while it is still in its unhardened condition, and prior to the stamping operations which shape the strip into unjoined blades, so that the edge operated upon by the cutting tools which form the bevels is continuous throughout the length of the strip and the material removed by each tool takes the form of a continuous filament.

Referring now to FIGURES 1 and 2 of the drawings, a strip 1 of razor blade steel, such as carbon steel in unhardened condition, is drawn from a storage roll whose axle 2 is indicated in FIGURE 1 and caused to travel continuously in the direction of its length along a subsantially straight path determined by guide means constituted by a channel member whose side flanges are shown at 3, after which the strip may again be reeled up on a roll whose axle is shown at 4, or it may pass directly to other apparatus for carrying out further manufacturing operations.

The guide channel is arranged to permit free movement of the strip 1 in the direction of its length while restraining the strip against transverse movement in its own plane. Means (not shown) are also provided for resiliently holding the strip down against the web of the guide channel. The side flanges 3 and the web of the guide channel are cut away locally at six points, three on each side, to expose the edges of the strip so that each of these edges can be acted on successively by three pairs of cutting tools 6, 7 mounted in holders R1, R2, R3, and L1, L2 and L3. As best seen in FIGURE 2, each pair of cutting tools comprises two cylindrical, rod-like tools which are set at angles of approximately 3 to the plane of the strip and are disposed on opposite sides of the strip. The cutting edge of each tool is formed by grinding an internal cone in the end of the tool, the cone angle being such as to give a rake angle of approximately 10 between the conical surface and a perpendicular to the plane of the strip as measured on the plane of the cutters. The cutters are set at an angle of approximately 30 to the direction of movement of the strip, so that the cutting edges of the tools extend transversely to the strip. The tools of each pair are slidably mounted for axial and rotary adjustment independently of each other, and are adjusted so that the cutting edges of the two tools are positioned directly opposite each other for the removal of metal simultaneously from both surfaces of the strip,

with each cutter supporting the strip against the thrust applied by the other cutter.

As the strip 1 is moved longitudinally through the apparatus, by means for example of the take-up roll axle 4 being rotated, it is drawn through the gaps between the respective pairs of cutters 6, 7 in interfering engagement with the cutting edges thereof, with the result that on each marginal portion of the strip, material is removed from both surfaces of the strip at three different stations. One edge for example is acted on by the pairs of cutters 6, 7 in the holders R1, R2 and R3 as follows in the manner illustrated in FIGURES 3, 4 and 5. The first pair of tools 6, 7 in the holder R1 pare from each surface of the strip a wedge-shaped filament which is continuous along the length of the strip, these cuts being indicated at C1 in FIGURE 3. Next to the tools 6, 7 in the holder R2 pare oif continuous filaments, the cuts being indicated at C2 in FIGURE 4, and finally the cutters in holder R3 make the cuts C3 indicated in FIGURE 5. Similar cuts are of course made adjacent the opposite edge of the strip by the cutters in holders L1, L2 and L3. Each marginal position thus has the final form indicated in FIGURE 5 with two bevels or facets on the upper and on the lower surface of the strip. It would of course be possible to produce three bevels or facets by arranging for the final cut C3 to intersect with each of the facets left by the first two cuts. Generally, when making three cuts, we prefer to remove approximately the same amount of material with the second cut as with the first, and approximately half that amount with the third cut.

It will be understood that FIGURES 3, 4 and 5 are of a diagrammatic character only, and are not intended to show exactly the angles of taper of the bevels nor the thicknesses and shapes of the filaments removed by the successively acting tools.

The cutting tools 6, 7 can be rotated continuously or intermittently about their axes to bring into use fresh portions of the circular cutting edges, which are of course concentric with the axes of the tools. The necessary rotation of the tools can be eifected by hand or by mechanical means.

The strip which has been formed with tapered but unsharpened edges in the manner described is subsequently subjected to the usual blanking and heat treating operations of hardening and tempering and is thereafter sharpened. The sharpening operation may be precisely similar to that employed in existing practice, except for the omission of the step of grinding the primary bevels, these bevels having already been formed by the preliminary cutting operation.

While the invention has bene particularly described in relation to the treatment of a strip of carbon steel, the method and apparatus could be adapted for the treatment of other metals such as stainless steel, with consequent adjustments in such details as the setting and rake angles of the cutting tools, which angles are given purely by way of example.

What is claimed is:

1. A method of making razor blades from a strip of metal, including the steps of moving the strip longitudinal- 1y past and between a pair of cutting edges each disposed transversely to the said strip to pare material from opposite surfaces of the strip adjacent .one longitudinal margin thereof, thereby reducing the thickness of the edge, producing a sharpened edge along the said margin of the strip, and subsequently severing the strip transversely of its length to form a plurality of individual blades.

2. A method in accordance with claim 1 wherein the strip is moved past and between a plurality of pairs of cutting tools spaced apart longitudinally of the strip, the tools of each pair having their cutting edges spaced 0pposite each other for the simultaneous removal of metal from opposite surfaces of the strip.

3. A method in accordance with claim 1 wherein the said pair of cutting edges remove material from each surface of the strip in the form of an elongated wedge-shaped filament which increases in depth towards the edge of the strip and is continuous along the length of the strip.

4. A method in accordance with claim 1 wherein each of the cutting edges is circular and is formed on a tool which is mounted for rotation about an axis concentric 'with the said edge, the tool :being rotated during the cutting operation.

5. Apparatus for paring material from opposite surfaces of a metal strip adjacent one longitudinal margin thereof, comprising guide means for guiding a strip of metal for longitudinal movement through the appartaus, a pair of cutting tools, each having a cutting edge disposed transversely to the direction of movement of the strip, the said edges being spaced apart in directions perpendicular to the plane of the strip, and means for moving the strip longitudinally between the said cutting tools in interfering engagement with the said cutting edges to effect a reduction in the thickness of one longitudinal marginal portion of the strip by paring material from both surfaces of the strip. p

6. Apparatus in accordance with claim 5, comprising a plurality of pairs of cutting tools arranged to act successively upon the same longitudinal margin of the strip, the two tools of each pair being positioned directly opposite each other for removing material simultaneously from opposite surfaces of the strip, and the successive pairs of tools producing a progressive removal of material from the strip.

7. Apparatus in accordnace with claim 5, wherein each of the cutting tools is in the form of a disc having a circular cutting edge, and is rotatable about an axis concentric with the edge in order to bring different portions of the cutting edge into use.

References Cited by the Examiner UNITED STATES PATENTS 544,796 2/1896 Roberts 51-285 FOREIGN PATENTS 408,118 4/1934 Great Britain.

WILLIAM W. DYER, 111., Primary Examiner.

G. A. DOST, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NOB 3,283, 665 NOvember 8, 1966 Maynard Richard Hobbs It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 16, strike out "to"; column 4, line 27, for "appartaus" read apparatus column 4, line 45, for "accordnace" read accordance line 54, for "544,796" read 554,796 --a Signed and sealed this 12th day of September 1967,

( L) Attest:

ERNEST W. SW'IDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A METHOD OF MAKING RAZOR BLADES FROM A STRIP OF METAL, INCLUDING THE STEPS OF MOVING THE STRIP LONGITUDINALLY PAST AND BETWEEN A PAIR OF CUTTING EDGES EACH DISPOSED TRANSVERSELY TO THE SAID STRIP TO PARE MATERIAL FROM OPPOSITE SURFACES OF THE STRIP ADJACENT ONE LONGITUDINAL MARGIN THEREOF, THEREBY REDUCING THE THICKNESS OF THE EDGE, PRODUCING A SHARPENED EDGE ALONG THE SAID MARGIN OF THE STRIP, AND SUBSEQUENTLY SEVERING THE STRIP TRANSVERSELY OF ITS LENGTH TO FORM A PLURALITY OF INDIVIDUAL BLADES. 